Skin Layers and Functions Quiz

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Questions and Answers

What is the typical thickness range of the stratum corneum, the outermost layer of the skin?

10 μm - 20 μm (correct)

0.8 mm - 1 mm

20 μm - 30 μm

5 μm - 10 μm

Which cells in the epidermis produce and distribute melanin granules?

Keratinocytes

Melanocytes (correct)

Langerhans' cells

Basal cells

What is the function of Langerhans' cells in the skin?

Production of melanin

Defense mechanisms operated by the immune system (correct)

Blood supply regulation

Generating keratinocytes

Which fibrous proteins are embedded in the dermis?

Collagen, elastin, reticulin Signup and view all the answers

Why does the dermis require an efficient blood supply?

To convey nutrients and remove waste products Signup and view all the answers

How far does the blood supply of the dermis reach from the skin surface?

~0.2 mm Signup and view all the answers

What is the primary function of nitric oxide in relation to skin pathogens?

Preventing infections Signup and view all the answers

Why is the intact skin considered an effective barricade?

Due to the small fractional area of the permeable appendageal shunt route Signup and view all the answers

Which type of UV light is the most damaging to the skin when exposed to sunlight?

UVB: 290 – 320 nm Signup and view all the answers

What main reaction follows irradiation of the skin with UV light?

Erythema Signup and view all the answers

How does the skin primarily help maintain the body temperature at 37°C in high temperatures?

Dilating blood vessels Signup and view all the answers

What is a primary target region for dermatologists according to the text?

Skin surface Signup and view all the answers

What is the primary effect of topical treatments on the skin?

Manipulating the barrier function of the skin Signup and view all the answers

In what layer of the skin do emollient preparations work to restore softness?

Horny layer Signup and view all the answers

Which type of skin absorption is crucial in transdermal drug delivery systems?

Passive Diffusion Signup and view all the answers

What is the primary goal of systemic drug delivery through the skin?

Maintaining uniform systemic drug levels Signup and view all the answers

Which law describes the rate of drug transport across the stratum corneum?

Fick’s Law of Diffusion Signup and view all the answers

What is the main purpose of transdermal therapeutic systems?

Providing systemic therapy without oral intake Signup and view all the answers

Which method involves designing a prodrug with an optimal partition coefficient for entering the skin barrier?

Prodrug Signup and view all the answers

What is the purpose of chemical potential adjustment in circumventing the horny layer barrier?

To optimize the bioavailability of a topical medicament Signup and view all the answers

Which method may produce supersaturated solutions leading to a theoretical maximum flux increase?

Chemical potential adjustment Signup and view all the answers

How is the drug flux through the skin related to its activity in the vehicle according to the text?

Directly proportional Signup and view all the answers

What is the primary function of the thickened skin in ichthyosis?

To reduce the skin's permeability Signup and view all the answers

Which method involves the use of high-velocity particles (Powderject) to circumvent the horny layer barrier?

Microneedles Signup and view all the answers

How does the skin of children differ in terms of permeability compared to adult tissue?

Children's skin has a greater surface area per unit body weight, making it more permeable Signup and view all the answers

How can skin regional sites affect cutaneous permeability?

Variations in SC thickness and skin appendage density impact cutaneous permeability Signup and view all the answers

In what way can supersaturated preparations be described according to the text?

Unstable and difficult to formulate Signup and view all the answers

Why might treating premature infants with caffeine via topical application be advantageous?

Premature infants may be born with no stratum corneum, allowing for topical drug application Signup and view all the answers

How does an increased blood flow affect transdermal absorption?

Increased blood flow decreases the time a penetrant remains in the dermis Signup and view all the answers

Why is facial skin generally more permeable than other body sites?

Facial skin has a thinner stratum corneum compared to other body regions Signup and view all the answers

Study Notes

Skin and Transdermal Delivery

The skin consists of three layers: the epidermis, dermis, and subcutaneous tissue
The epidermis is the outermost layer, comprising 15-20 rows of flat, dead, keratinized epidermal cells
The dermis is 3-5 mm thick and consists of a matrix of fibrous proteins, blood vessels, and nerve endings
The dermis needs an efficient blood supply to convey nutrients, remove waste products, and regulate pressure and temperature

Barrier Function of the Skin

The intact skin is a very effective barricade due to the diffusional resistance of the horny layer and the permeable appendageal shunt route
The horny layer is very impermeable to most chemicals and usually contributes the rate-limiting step in transdermal absorption
The skin is the primary organ responsible for maintaining the body at 37°C

Skin Function and Temperature Regulation

At high temperatures, the body loses heat through blood vessel dilation, eccrine sweat gland secretion, and evaporation
At low temperatures, the body conserves heat by shutting down peripheral circulation and generating energy through shivering

Target Regions for Dermatologists

Skin surface
Epidermis
Dermis
Subcutaneous tissue
Systemic circulation

Skin Age and Permeability

Skin of young and elderly is more permeable than adult tissue
Children and premature infants have greater surface area per unit body weight, making them more susceptible to toxic effects of drugs and chemicals

Factors Affecting Transdermal Absorption

Changes in peripheral circulation could affect transdermal absorption
Regional skin sites have variations in cutaneous permeability depending on the thickness and nature of the SC and density of skin appendages
Facial skin is generally more permeable than other body sites
The horny layer barrier can be circumvented by methods such as prodrugs, chemical potential adjustment, hydration, ultrasound, iontophoresis, stratum corneum removal, microneedles, penetration enhancers, ion pairs, and high-velocity particles

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Description

Test your knowledge on the topical horny layer, viable epidermis, upper dermis, dermal skin glands, and systemic circulation. Learn how different skin layers affect the barrier function, absorption of drugs, and protection from external factors.